Super sized electromagnetic coils are helping explain how aquatic life might be affected by renewable energy devices being considered for placement along America's coastal waters and in the nation's rivers. An electromagnetic field is a physical field produced by electrically charged objects. It affects the behavior of charged objects in the vicinity of the field. The effect on marine life is not known one way or the other.

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Scientists with the Department of Energy's Pacific Northwest National Laboratory are examining whether a variety of fish and invertebrates change their behavior during and after exposure to an electromagnetic field similar to those produced by marine and hydrokinetic power devices that capture energy from ocean waves, tides, currents and rivers.

Energy companies and utilities are looking at using several different technologies to harness energy from oceans and rivers. Marine power could come from devices that move with rolling waves on the ocean's surface or from underwater turbines that spin with the tides and currents. Hydrokinetic devices would be similar to marine power devices, but generate power from free-flowing water in rivers and streams. Whatever the design, each device generates electricity that travels through cables that connect the device with a land power line. Researchers want to know how the devices and their cables affect marine life.

Researchers want to know if the electromagnetic field will also affect marine and estuarine animal behavior, including migration, finding food and avoiding predators. Several aquatic animals - such as sharks, skates, salmon, sea turtles and lobsters - may use the Earth's natural magnetic fields like a compass to navigate and detect their prey.

To test the field's potential effects, aquarium tanks filled with marine species are being placed near the two coils. Then researchers will activate the electromagnetic field - at various strengths and time periods - to see if the animals' actions change.

For example, researchers will observe whether the electromagnetic field interferes with the ability of juvenile Coho salmon to recognize and avoid predators. Young salmon normally stop swimming, go low and stay still when they detect a predator. Researchers will document whether the animals are attracted or repelled by the fields.

The effect of electromagnetic fields on life forms is not well studied. Some birds and marine life migrate apparently reacting to the Earth's magnetic field for orientation.

The best understood biological effect of electromagnetic fields is to cause heating. For example, touching or standing around an antenna while a high-power transmitter is in operation may cause burns.

Many subtle, and at times, not-so-subtle effects on behavior have been reported from exposure to electromagnetic fields while other effects have been disproved. The current study will help focus attention on this poorly understood area of science and biology.